The present invention relates generally to printing machines, and more particularly, is directed to a shield for a doctor blade holder.
Conventionally, in printing machines, such as flexographic printing machines, an ink transfer or anilox roll transfers ink to an adjacent plate roll for printing. Ink is supplied to the anilox roll from an ink chamber defined by a chamber housing which partially surrounds the anilox roll. Specifically, ink is supplied through an ink supply tube and then through an ink supply line in the chamber housing, into the ink chamber. In like manner, ink is removed from the ink chamber through an ink return line in the chamber housing and then through an ink return tube.
In order to prevent the escape of ink from the chamber, while ensuring that the ink enters the cells in the anilox roll and has a predetermined thickness on the anilox roll, doctor blades are provided at the entry and exit positions of the anilox roll relative to the ink chamber. The doctor blades are fixed to the chamber housing by a clamp so that the doctor blades overhang the chamber housing and contact the anilox roll.
With this arrangement, the outer surface of the anilox roll passes through the ink chamber and picks up ink for printing. The ink is metered by means of the doctor blades held to the inlet and outlet ends of the chamber housing, with the free ends of the doctor blades being in contact with the outer surface of the anilox roll. The doctor blades are clamped to a chamber housing by a clamp holder.
In such case, ink may leak around the doctor blade and ride on the outer surface of the doctor blade so as to deposit on the outer surface of the chamber housing. Additionally, ink may be deposited on the outside of the chamber by operator error or by a worn doctor blade blowing out. Further, the sealing blade on the chamber may pick up ink from the anilox roll and deposit the ink on the outside of the chamber, an event called back blading. Ink on the outside of the chamber requires an extensive clean-up operation which is burdensome and time-consuming.
Gravure printing has a similar process wherein a doctor blade is held by a clamp or holder. Spills and operator error result in ink being deposited on the clamp or holder, requiring extensive clean up.
Accordingly, it is an object of the present invention to provide a shield for a doctor blade holder that overcomes the aforementioned problems.
It is another object of the present invention to provide a shield for a doctor blade holder that prevents ink droplets from falling on the outer surface of the ink chamber housing or other holder that holds the doctor blade.
It is still another object of the present invention to provide a shield for a doctor blade holder that covers the outer surface of the ink chamber housing or other holder that holds the doctor blade.
It is yet another object of the present invention to provide a shield for a doctor blade holder that prevents ink from falling on the outer surface of the holder or clamp housing.
It is a further object of the present invention to provide a shield for a doctor blade holder which hangs down in covering relation to the outer surface of the ink chamber housing or other holder that holds the doctor blade.
It is a still further object of the present invention to provide a shield for a doctor blade holder which wraps around and is secured to the outer surface of the ink chamber housing or other holder that holds the doctor blade.
It is a yet further object of the present invention to provide a shield for a doctor blade holder in which the shield and doctor blade are secured to each other to form a unitary unit.
In accordance with an aspect of the present invention, for use with a doctor blade holder of a printing machine, a combined doctor blade and shield includes a doctor blade adapted to be secured to the doctor blade holder in a manner so as to extend outwardly therefrom at least substantially in engagement with an outer surface of a roll for metering ink on the roll, the doctor blade being formed as a doctoring plate having a rear portion adapted to be secured to the doctor blade holder and a front portion with a doctoring edge adapted to at least substantially contact the outer surface of the roll to meter ink thereto, and a doctor blade shield having one end fixedly secured to the doctor blade in spaced relation away from the doctoring edge and a second opposite free end unsecured to the doctoring plate, so as to cover at least a portion of the outer surface of the doctor blade holder to prevent ink from depositing on the outer surface of the doctor blade holder when the combined doctor blade and doctor blade shield is clamped to the doctor blade holder.
The shield can be flexible or rigid. In one embodiment, the shield hangs down from the one end in at least partial covering relation to the outer surface of the doctor blade holder. In another embodiment, the shield has a second opposite end secured to the outer surface of the doctor blade holder at a position remote from the one end. In such case, the shield is wrapped at least partially around the outer surface of the doctor blade holder, and there is a securing arrangement on the outer surface of the doctor blade holder for securing the second opposite end of the shield thereto.
In one embodiment, the doctor blade holder is formed as part of an ink chamber housing, and in another embodiment, the doctor blade holder is part of a gravure printing apparatus.
In accordance with another aspect of the present invention, for use with a machine, a combined doctor blade and shield includes a doctor blade formed as a doctoring plate having a rear portion to be secured to a holder of the machine and a front portion with a doctoring edge adapted to at least substantially contact an outer surface of an element to be doctored, and a doctor blade shield having one end fixedly secured to the doctor blade in spaced relation away from the doctoring edge and a second opposite free end unsecured to the doctoring plate, so as to cover at least a portion of an outer surface of the holder when the combined doctor blade and shield is secured to the holder.
In accordance with still another aspect of the present invention, a printing machine includes an ink well positioned adjacent a rotating ink roll; a doctor blade holder positioned adjacent the ink roll; a doctor blade adapted to be secured to the doctor blade holder in a manner so as to extend outwardly therefrom at least substantially in engagement with an outer surface of the ink roll for metering ink on the roll, the doctor blade being formed as a doctoring plate having a rear portion adapted to be secured to the doctor blade holder and a front portion with a doctoring edge adapted to at least substantially contact the outer surface of the roll to meter ink thereto; and a doctor blade shield having one end fixedly secured to the doctor blade in spaced relation away from the doctoring edge and a second opposite free end unsecured to the doctoring plate, so as to cover at least a portion of the outer surface of the doctor blade holder to prevent ink from depositing on the outer surface of the doctor blade holder when the combined doctor blade and doctor blade shield is clamped to the doctor blade holder.
The above and other objects, features and advantages of the invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings.